"Osama bin Laden may use this method to sneak in to the US."
There are so many ways that snow globes can harm somone.
The most obvious is that you could replace the water within with a clear water-like explosive substance, of the sort that doesn’t actually exist.
You could also simply bash someone with one in the back of their skull, rendering them unconscious, or shatter the globe and use the resulting shards of glass as a crude blade-like weapon.
And, of course, you could simply shake the globe, letting the falling snow cause your target to go into a reverie, flashing back to the childhood sled that represents his lost innocence.
While we are still subject to these sorts of attacks as we walk the streets, we at least know that on airplanes we will be safe, thanks to the heroes at the TSA.